Display cabinets such as coolers and freezers contain a number of conventional shelves on the interior of the cabinet in which products are displayed. Typically, the cabinet has a door having a large transparent panel through which the products on the shelves are viewed. Between the cabinet door and interior shelving there is usually dead space due to the cabinet wall thickness. This dead space can be used by mounting a rack on the interior surface of the transparent panel of the door. Since the panel is usually made of glass or a plexiglass material, attachment means typically extend to the frame of the panel resulting in an obstructed view of the products enclosed in the cabinets. Preferably the rack should not obstruct the customer's view of the products and should be moveable and yet have a large load carrying capacity.
Department stores, convenience stores and other retail shops often have windows which are used to display goods. These windows typically display a limited selection of goods because the goods are usually arranged on a table, a staged floor or some other prop. Shelving can be constructed adjacent or in the window, but structural members of conventional shelving obstruct the customer's view of the goods on display or the interior of the store. Preferably the rack shelf should be lightweight and mountable on a large pane of glass adjacent the sill of a window or floor to optimize its load carrying capacity.
Suction devices are commonly used to mount and secure objects to smooth surfaces such as the surfaces of glass, plastic, formica, glazed tile, metal, etc. The typical suction device includes a cup body and a stem. The cup body is generally arcuate or circular and defines a concavity. Typically the stem is integrally formed on the body and used as the place of attachment for the object to be supported by the suction cup device. At least the body of the suction device is made of rubber, plastic or other material having sufficiently resilient properties such that when the body is pressed against a smooth surface the volume of concavity is reduced, forcing air to be expelled so that the body forms an air-tight seal against the smooth surface. Atmospheric pressure outside the body retains the cup body against the surface. When the air-tight seal is broken, air rushes into the concavity, releasing the suction attachment to the surface and the resilient material of the cup body returns to its relaxed condition. The resilient suction cup device can be repeatedly reused.
Problems often arise in use of suction devices in that they are difficult to properly position. Once a suction device is attached to a surface, the suction forces (atmospheric and friction) resist repositioning of the cup. Attachment of the suction device to an object can also be a problem. Preferably, the attachment should be releasable.
U.S. Pat. No. 2,221,238 to S. L. Johnson discloses a suction cup having normally closed slits in the stem communicating with the concavity of the suction cup body and a C-shaped clamp for connecting an object to the stem. The suction cup is particularly adapted for mounting a vibrating object such as a typewriter to a horizontal surface. The slits operate similarly to a one-way valve. When the suction cup is pressed against a surface (during installation or downward vibration of the object) air pressure developed in the compressed concavity of the suction cup is expelled through the slits, resulting in creation of a vacuum within the cup body. Outside atmospheric pressure acting on the stem tends to keep the slits closed, thus preventing the entrance of air into the cup. When the body is forcefully lifted vertically away from the surface, the C-shaped clamp presses upwardly against the stem, which stretches the walls of the stem, thereby opening the vent slits and permitting air to enter into the cup to relieve the vacuum and release the cup from the supporting surface.
U.S. Pat. No. 2,319,727 to J. E. Duggan discloses a vented suction cup having a valve in the suction cup body. When it is desired to remove the cup structure from the mounting surface, the valve is pulled sufficiently to distort the rubber and open an air passage. Thus, air from the atmosphere may enter the body of the suction cup to destroy the vacuum and release the cup from the mounting surface.
U.S. Pat. No. 4,196,882 to Rognon discloses a double suction cup holder in which two oppositely oriented suction cups are connected by a shared stem. The double suction cup holder can be used to secure objects such as memo pads to a flat surface. A longitudinal air passageway through the stem connects the concavities of the two cups. An opening traverses the passageway and has a valve member rotatably positioned therein. The valve member has inter-communicating longitudinal and diametrical bores. When the valve is turned so that its diametrical bore communicates with the air passageway in the stem, the vacuum in the cups is spoiled, thereby releasing the cups from the two surfaces.
Another problem arises when a large load is to be carried by suction devices. One solution is to increase the suction cup size, thereby increasing the force needed to remove the suction device from the surface to which it is mounted, but the maneuverability of the device is decreased. Another solution is to use two or more suction devices. However, in the typical arrangement the suction devices are mounted so that the load is not evenly distributed between the suction cups and the load will cause one of the devices to become disengaged before the other. As a result, when the first cup fails, the second suction cup experiences the full load and it too becomes disengaged. Preferably, a rack employing suction devices which is to carry a large load should minimize the size of the suction devices and maintain the rack's adjustability without compromising its load carrying capacity.